This invention relates to a buoyancy control device for scuba divers and more particularly to a buoyancy control device for controlling the vertical motion of a scuba diver under normal and emergency conditions.
Buoyancy compensators for scuba divers are well known for use in controlling buoyancy while diving. Such compensators typically consists of a flexible air bladder and hand-activated pneumatic fill and release valves. In this manner, the buoyancy force acting on the diver is changed by adjusting the volume of air in the flexible bladder.
Such compensators generally require careful attention from a diver to attain and maintain neutral buoyancy, to safely descend, to safely ascend and to establish adequate positive buoyancy at the surface. The diver controls buoyancy by using the hand-activated air valves to add and release air to and from the buoyancy compensator. Such control is based on vertical motion changes, references to stationary objects or the use of a depth gauge.
Neutral buoyancy is achieved at a selected depth and must be adjusted as the depth of the dive changes. A deviation from neutral buoyancy also occurs due to changes in the hydrostatic pressure of the water which changes in depth as well as changes in the loss of weight as air from the compressed air tank is used.
An improved buoyancy compensator that reduces the scuba divers attention and exertion required for buoyancy control is disclosed in the U.S. Pat. No. 5,496,136 of Egan. As disclosed therein, a buoyancy compensator includes an electronic sensor/valve assembly and a flexible air bladder which automates and controls the vertical motion of a diver. A computer acquires pressure, temperature and air flow data to determine the diver""s vertical motion and the amount of air in the bladder. The computer controls electronic fill and release valves to change the volume of air in the bladder. Algorithms are implemented by the computer to automate controlled vertical propulsion for ascending, descending, neutral buoyancy, maintenance and surface operation. Automated transitions are provided between modes of operation and for a timed safety stop during the ascent from the dive.
Another approach for an improved buoyancy compensator device is disclosed in the U.S. Pat. No. 5,560,738 of Noel. As disclosed therein, a depth sensitive diver safety system is utilized with an underwater breathing apparatus. The system includes a first automatic ascent control stage which initiates gradual regulated inflation of a personal flotation device from a pressurized air source when a user drops below a danger/low air level corresponding to a diver""s depth. The system also includes a second automatic ascent control stage which is structured to initiate gradual, regulated inflation of the personal flotation device upon the diver""s depth exceeding a pre-set depth level. The 5,560,738 patent is incorporated herein in its entirety by reference.
A more recent approach to buoyancy compensators is disclosed in the U.S. Pat. No. 5,746,543 of Leonard. The Leonard patent discloses a volume control module for controlling the buoyancy of a diver by controlling the volume of air in a buoyancy chamber of a buoyancy compensator. The Leonard device is used in conjunction with underwater equipment which is provided with an adjustable buoyancy chamber. The Leonard patent is also incorporated herein in its entirety by reference.
Notwithstanding the advances disclosed in the aforementioned patents, it is presently believed that there is a need and a commercial demand for an improved buoyancy control device. It is believed that there is a need for a device in accordance with the present invention that provides buoyancy control without excessive diver attention through all phases of the dive. In addition, the buoyancy control device in accordance with the present invention provides for automated compensation for changes in buoyancy of a scuba tank as the air is consumed by a diver.
A further advantage of the buoyancy control devices in accordance with the present invention is that they provide automatic vertical propulsion and vertical velocity control of a diver during the descent portion of the dive and also during the ascent portion of the dive. A still further advantage of the present device is the inclusion of a safety feature that allows a diver or a second diver to provide for a relatively fast ascent under an emergency with a limited risk of a lung expansion injury or decompression sickness.
Further, the improved device in accordance with the present invention allow a second diver to send an injured or unconscious diver to the surface unaccompanied by the second diver at a controlled rate. In addition, it is believed that the devices in accordance with the present invention can be manufactured at a competitive price, and are reliable and durable.
In essence, the present invention contemplates an improved buoyancy control device for scuba divers. The device includes a buoyancy compensator or vest to be worn by or attached to a diver. The device also includes one or more compressed air tanks adapted to be carried by a diver in a conventional manner and means such as a depth or pressure gauge for measuring the depth of a diver. A valve or other means is connected to the buoyancy compensator and the compressed air tank for releasing air from the compressed air tank into the buoyancy compensator and for releasing air out of the buoyancy compensator. The device also includes a microprocessor operatively connected to the means for measuring the depth of the diver and to the valve for controlling the amount of air in the buoyancy compensator in response to the depth of a diver. In addition, the device includes means for inputting a first selected rate of ascent for controlling the vertical movement of a diver under normal conditions and a second selected rate of ascent for controlling the vertical movement of a diver under emergency conditions. An additional element in the device is means accessible by a second diver for overriding the first rate of ascent and activating the second rate of ascent. In this way, a disabled or unconscious diver can be safely sent to the surface without escort by a rescuing diver at a rate which is greater than normal but acceptable under emergency conditions.